Poor performance with external Samsung monitor.

Discussion in 'Mac and PC Games' started by lolzok, Aug 19, 2011.

  1. lolzok macrumors newbie

    Jul 5, 2011
    Hey everyone,

    I've been playing World of Warcraft for a while on my mbp without an external monitor. I have the settings set to pretty much max out everything - runs great on the mbp with its native resolution of 1920x1200. I even had to limit the fps to 60 and it almost never drops below 40-ish.

    Now I've bought a Samsung Syncmaster P2270HD and connected it to the mbp with a mini-dvi->hdmi converter and an HDMI cable. The monitor is a 22" and has a native resolution which is actually lower than the mbp's - 1920x1080. But when I try to run WoW with the external monitor connected it runs really, really bad - we're talking 15-20 fps!

    I don't see how this makes sense at all, and I hope that one of you guys know a solution to my problem.

  2. asdf542 macrumors 6502

    Oct 26, 2010
    Any time you connect to an external monitor your available VRAM is being cut in half(more or less) which in turn will cause a drop in performance. Try lowering the resolution of the game or external monitor.
  3. AdrianK macrumors 68020

    Feb 19, 2011
    And exactly half is designated to each monitor? That can't be right, surely it would be allocated to where it's needed?
  4. Nuttydev, Aug 19, 2011
    Last edited: Aug 20, 2011

    Nuttydev macrumors 6502

    Mar 6, 2009
    Bristol, England.
    Are both the screens on? If so, shut the lid of the laptop then wake it up with an external keyboard (so the external monitor is the main and only monitor) and you should have your frame rate back.
  5. asdf542 macrumors 6502

    Oct 26, 2010
    Feel free to do your own research on the subject or find something that says otherwise.


  6. AdrianK, Aug 19, 2011
    Last edited: Aug 19, 2011

    AdrianK macrumors 68020

    Feb 19, 2011
    Question marks generally indicate a someone questioning something, ergo not stating a fact. :roll eyes:

    That's fair enough, it would be nice to see a citation for the claim though. LULZ @ DOWNVOTEZ []_[]
  7. gnasher729 macrumors P6


    Nov 25, 2005
    I'd say the author of that article was just guessing and hasn't done any research on his own.

    There is a small amount of video memory that will be reserved for a monitor, just enough for double buffering and Z buffer. Make that about 10 byte per pixel, maybe 12 if they use a floating point Z buffer.

    Everything else is dynamically allocated. There is memory needed for the backing buffer of a window; but two large windows use exactly the same amount of video memory whether they are on one or on two monitors.
  8. AdrianK macrumors 68020

    Feb 19, 2011
    I've just performed a test with similar conditions to the OP using Portal:

    MacBook 1024*768 for Portal - 25-34 FPS
    MacBook 1024*768 showing desktop, monitor 1024*768 for Portal - 20-26 FPS :eek:

    Same settings used for both, both fullscreen (windowed didn't make a difference), tested on a 9400M.

    I'm quite surprised :(
  9. lolzok thread starter macrumors newbie

    Jul 5, 2011
    Isn't there some way to completely turn of the mbp's monitor? It's unbelievable to me that a monitor with lower resolution will cause as poor performance as it does :(
  10. gnasher729 macrumors P6


    Nov 25, 2005
    You can try turning on mirroring; don't know what effect that would have on timing. To disable the internal monitor, you need an external mouse and keyboard; keep the lid close and wake the MacBook up by pressing any key on the keyboard.

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